ML20116F592
| ML20116F592 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 11/05/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20116F584 | List: |
| References | |
| NUDOCS 9211100412 | |
| Download: ML20116F592 (4) | |
Text
.
~ - - _ _
t-'
+p*M44
]
4 --
o UNITED STATES.
T E "
I,,c -
NUCLEAR REGULATORY COMMISSION 2-WASHINGTON, D. C. 00555,
1*-
_g c
sE.../
i SAFETY EVALUATION BY-THE OFFICE OF NUCLEAR REACTOR' REGULATION 3
RELATED TO AMENDMENT NOS. : 45 AND 34 T0-FACIllTY OPERATING LICENSE NOS. NPF-76=AND-NPF-80 HOUSTON LIGHTING & POWER COMPANY 1
CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY CITY OF AUSTIN. TEXAS R0.CKET NOS. 50-498 AND 50-499 e
SOUTH TEXAS PROJECT. UNITS 1 AND 2
1.0 INTRODUCTION
By application dated August 30, 1991 (ST-HL-AE-3842) as-superseded by h
application dated June 2, 1992 (ST-HL-AE-4049),' Hor ton l Lighting.& Power Company, at.al~., (the licensee) requested changes to the. Technical' Specifications (Appendix A te' facility Operating License Nos. NPF-76 and NPF-80) for the South Texas Project, Units 1 and 2.
The proposed;cheages would change the logic for the Unit I toxic gas monitors in concert with-replacing the two original toxic gas monitoring channels-with-three state-of--
the-art toxic. gas monitoring channels. The actuation logic would be revised to provide a -two-out-of-three (2/3) logic.for a high toxic gas actuatior-signal' and monitor failure ~. actuation logic, asc opposed to the current 4 one-out-
- of-two (1/2) and two-out-of-two:(2/2) logic, ~ respectively. - The submittal also:
proposed that-an inoperable channel-be bypassed for~up to 4! hours for.-
surveillance. testing..The toxic gas monitors andztheir associated logic
~
actuate the heating, ventilation, and air; conditioning (HVAC) envelope for-operator-protection if there is a release 'of vinyl acetate, anhydrous-ammonia, or ammonium hydroxide.
The June 2,1992, letter also requested that an interim Technical Specification be approved for the current Unit l refueling outage and a final-Technical Specification be approved in February 1993 to support the Unit'2 o
refueling outage.
This would allow time -for' the appropriate hardware and
. procedural changes to be -.made for each refueling outage. This Safety _
Evaluation supports the-' approval of the proposed. interim Technical Specification 3/4.3;3.7.
-7 90 0
e L.
. 2.0 [ VALUATION In reviewing the original design and logic for the toxic gas monitoring system, the staff reported in Section 6.4 of its Safety Evaluation (Safety Evaluation Report related to the Operation of South Texas Project, Units 1 and 2, NUREG-0781) that during a postulated hazardous chemical release the detection, alarm, and automatic isolation capabilities at South Texas will ensure that control room personnel can don breathing apparatus before the toxic gas concentration in the control room could exceed the applicable toxicity limits.
The licensee proposes to add a third monitor channel and change the actuation from one-of-two-logic to a two-of-three logic. New state-of-the art hardware will be installed for the new channel and the existing channels will be replaced to ensure longevity and adequate spare parts supply. The loss of power / malfunction actuation will also be changed from a one-of-two logic to a two-of-three logic.
The proposed changes are controlled by the licensee's Modification 91-015 and 91-016. The equipment purchase is controlled by specification. Due to the nature of this service, hardened laboratory grade instrumentation is required; therefore, the licensee awarded the purchase contract bid based on technical merit, equipment historical reliability and availability of vendor support. As stated in the FSAR, the equipment has not been qualified for seismic conditions.
The three monitor channels are powered from three-non-safety uninterruptible power supplies (UPS). The associated batteries for two of the UPSs receive power from chargers that are supplied power from motor control centers (MCC) associated with the Class IE Emergency Diesel Generators (EDG). The other UPS associated battery is supplied power from two charge <s one of which receives power from a MCC associated with another EDG. This diversity of power supply provides increased reliability.
Both the monitor and loss-of-power actuation logic provide-improvea operability and reliability goals for the system by reducing spurious actuation. The licensee has estimated that, based on statistical analyses, the decrease in the probability of actuation resulting from the proposed modification upon demand is small (0.002); however, there will be a significant decrease in probability of spurious actuation. Allowing maintenance of a bypassed channel will reduce the possibility of spurious actuation into the recirculation mode which is less conservative with regard to responding to a radiological accident.
The existing Technical Specification (TS) 3.3.3.7 action statement for an inoperable chemical detection system (toxic gas monitoring) requires the system be restored to operable within 7 days or within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> initiate and maintain operation of the control room emergency ventilation systen in the recirculation mode of operation. The action statement also states -if two chemical detection system channels are inoperable, within I hour initiate and maintain operation of the control room emergency ventilation system in the recirculation mode of c,peration.
. The proposed (for Unit 1) TS action statement for an inoperable chemical detection system channel requires the system channel be restored to operable within 7 days or place the affected channel in its tripped condition.
If two or more chemical detection system channels are inoperable, the proposed action statement is the same as the present action statement.
The only chcnge to the surveillance requirements is that the word digital has been added to the analog channel operation test.
3.0
SUMMARY
The staff finds the toxic monitor system modification, the change to the Technical Specification Section 3.3.3.7 Limiting Condition for Operation, and Section 4.3.3.7 Surveillance Requirements acceptable.
The modification should improve the reliability of the system and decrease spurious actuations.
The TS changes will provide operability of the system consistent with the original TS; however, it also allows for greater flexibility by allowing operation with-an additional channel out of service because of the addition of the third channel.
The interim technical specification retains the current requirements for Unit 2, which still has the two logic channels while incorporating the new action statements and surveillance for Unit 1.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Texas State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within thi restricted area as defined in 10 CFR Part 20 and changes surveillance requirements.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any ef fluents that may be released offsite, and that there is no significant intrease in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (57 FR 45643). Accordingly, the' amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
.=
8
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributo. :
F Paulitz Date: November 5, 1992 l
l
.